Appreciate if anyone can help regarding my U2515H not being able to play sound from attached AC511 Soundbar. U2515H attached to a Macbook Air via display port cable. AC511 has power to it (attached to power USB on U2515H) so that isn't the problem, but when changing sound on Macbook from internal speaker to U2515H it says 'The selected device has no output control', and the output volume control is greyed out. Dell are hopeless as they say there monitors do not support Macs, what a copout. Thanks for any help with my problem.